It is desirable in certain situations to be able to connect electrical devices through the use of flexible cables, in such a manner that a cable can easily be separated from a circuit module and reconnected thereto or to a similar circuit module. In some cases such cables may contain many conductors or coaxial pairs of conductors, each of very small size, while it is necessary, nonetheless, to achieve reliable electrical interconnection of each conductor with the circuit module, and to do so without the connector having a significant effect on the impedance of the combination of the cable and the circuit module. At the same time, it is commonly desired for the size of an electrical connector to be no greater than is necessary consistent with reasonable cost and difficulty in assembly thereof.
Particularly where many conductors of a flexible cable connected to larger, stationary, portions of complex electronic devices are to be connected to portable electrical circuit modules such as hand-held signal input or output devices, it is desirable to minimize the size of cable connectors, so that the connectors do not unnecessarily impose restrictions on the convenience of use portable of the circuit modules. For example, it is desirable to allow as much freedom of movement as is practical for a hand-held transducer module connected by a cable, including as many as one hundred or more coaxial conductor pairs, to a stationary control and display console of a diagnostic medical ultra-sound apparatus.
It has previously been costly to design small connectors to fit cables for specific cables and circuits, adding greatly to the cost of each unit where there are only relatively small numbers produced. It is therefore desirable to minimize the cost to design and manufacture a multi-conductor connector specifically intended for a particular application, where a cable to be connected includes many conductors of a particular size and the connector is to be as small as practical.
Many developments have been made to provide small connectors with high contact density and reliable performance. For example, Adams U.S. Pat. No. 5,108,313 discloses a modular connector for multi-conductor cables, in which respective groups of conductors of a cable are attached to each of several modules each carrying a corresponding number of pin contacts. The modules are clamped together and held in a predetermined arrangement by a housing which unifies the several modules as an integral connector. The individual conductors of the cable, however, are spread apart from one another within the connector modules and the housing, and the connector therefore is larger than is desirable, as a result of the pin contact spacing.
Tengler et al. U.S. Pat. No. 4,484,792 discloses another modular electrical connector including spring contacts located within sockets. The individual conductors of a cable connected using the connector are spaced somewhat apart from each other to achieve connection to the connector. Thus, the connector disclosed is larger than desirable and does not provide as high a contact density as is desired in some applications.
Kozel U.S. Pat. No. 4,243,289 discloses a modular connector in which an array of contact pins includes several similar modules each containing a group of the contact pins. The contact pins, however, are spaced apart farther than is desirable for a high-density connector in a situation where space is limited or small size is highly desirable.
Mori U.S. Pat. No. 5,176,541 discloses a connector incorporating brass strips formed on a carrier and thereafter partly covered with plastic material molded onto the strips. The plastic material holds and supports portions of the brass strips, leaving other portions exposed as contacts, but with electrical contact being available only along exposed lateral faces of contact portions of the strips. The connector, moreover, is not well adapted to connecting a cable to a grid-like planar array of terminals as may be present on a printed circuit board.
Massey U.S. Pat. No. 4,087,655 discloses a connector including several modules to which pairs of conductors can be connected. The connector defines receptacles for pin contacts opposite the connected conductors, but does not provide contact density as high as is desired for some applications such as those mentioned previously.
What is desired, then, is a connector and a method for manufacturing such a connector to provide a high contact density, for achieving connection of all of the conductors of a multi-conductor cable to respective terminals of conductors of a circuit module in a minimum amount of space, but without the connector being overly expensive to manufacture. It is also desired to provide such a connector which may readily be manufactured in various sizes, to connect cables including various numbers of conductors of various sizes to corresponding arrays of terminals.